Bacteria in fermented foods can give flavour helping hand

The interactions between flavour compounds and bacteria in fermented foods could enable formulators to maximise the taste of their products, suggests new research.

A study using two strains of Lactococcus bacteria showed that, depending on the strain and its surface properties, the compounds associated with cheese flavour (ethyl acetate and ethyl hexanoate) could be better retained in a model emulsion system.

The study is to be published in an upcoming edition of Food Hydrocolloids.

"With the great diversity of bacterial surface properties, it is possible to select strains possessing adequate surface properties in addition to the right metabolic characteristics to reach the optimal behaviour in food matrix," wrote the authors from France's Institute National de la Recherche Agronomique (UMR UB/INRA 1232), Dijon.

"This study constitutes a first step in the field of interactions between cells and aroma compounds."

How consumers sense food is crucial knowledge for a food industry constantly organising the building blocks of new food formulations.

According to background information in the article, micro-organisms can alter the properties of an emulsion, which has knock-on effects to how flavour and aroma is released, and subsequently perceived.

"However, the interactions between bacteria and aroma compounds have not received so much attention despite the presence of bacteria in many fermented products," stated the authors.

In a first step to redress this imbalance, the researchers chose two Lactococcus lactis subsp. lactis biov. diacetylactis strains, designated LLD16 and LLD18, and tested the retention of ethyl acetate and ethyl hexanoate in a model emulsion.

As the researchers anticipated, the bacteria affected the release of the aroma compounds, with the effect dependent on the bacterial surfaces and the physicochemical properties of the aroma.

Indeed, they report that aromas were not retained at all in the presence of LLD18. On the other hand, the presence of LLD16 significantly improved ethyl hexanoate retention and release from the emulsion.

The order at which the ingredients was added - bacteria or ester first - was also found to affect the flavour retention. The results show the potential of bacteria to boost flavour in emulsion formulations.

"After this demonstration of the impact of bacteria on flavour retention, it will be interesting to characterize the nature of the interactions particularly by working with different bacterial strains and aroma compounds from different chemical classes and different physicochemical properties," wrote the authors.

"The evaluation of the physiological consequences of interactions between living bacteria and aroma compounds, i.e. how bacteria modulate their surface properties depending on the presence of aroma compounds, would also be of interest to enable to predict the retention of volatile compounds by microorganisms," they concluded.

Taste is a key driver in the €3.2 trillion global food industry and a greater understanding of the physiology of consumers, could lead to strong market advantages.